1. Field of the Invention:
The present invention relates to improvements in refrigerating apparatus. The present invention particularly concerns a refrigerating apparatus such as refrigerator, freeze stocker, refrigeration or freezing show-case etc. which employs a hermetically sealed compressor of the high pressure type, especially a rotary compressor having a fluid check valve in its refrigerant circuit.
2. Description of the Prior Art:
Generally, in small type refrigerating apparatus having a closed type high pressure compressor, such as, a rotary compressor, the space in the compressor housing is under high pressure. Accordingly such refrigerating apparatus requires a considerably larger volume of refrigerant in comparison with the conventional low pressure closed compressor, such as a reciprocation type compressor. As one example, a home use freezer refrigerator of the reciprocation type compressor needs about 150 gr of refrigerant, but the rotary compressor type home use freezer refrigerator of the same size requires about 250 gr of refrigerant which is about a 50% or more increase. The increment portion, namely 100 gr of refrigerant, exists partly as a high temperature and high pressure super-heated gas and partly as liquid phase gas mixing in the compressor oil. At the time immediately after the compressor is stopped by a thermostat, the gas phase and liquid phase of parts the refrigerants are heated, with the liquid phase being vapourized into the gas phase, by high temperature parts of the compressor. Thereby, both parts become high temperature and high pressure super heated gas, which flow back to an evaporator connected to the refrigerant inlet port of the compressor. The above-mentioned situation of the general operation scheme of the conventional rotary type compressor is elucidated with reference to FIG. 1.
The refrigerant circuit connects from a rotary compressor 1 through a condenser 4, a capillary tube 6, as a pressure decreasing member, an back evaporator 7 and to the rotary compressor 1. The refrigerant gas is compressed by the rotary compressor 1 and issued as a high temperature and high pressure super heated gas and delivered to the condenser 4, where the gas is cooled to normal temperature and is delivered through the capillary tube 6 where the refrigerant is changed to a liquid phase, and fed to the evaporator 7. When the compressor motor stops usually by means of operation of thermostat (not shown), the high temperature and high pressure super heated gas in the rotary compressor housing 2 goes out on one hand through the condenser 4 and capillary tube 6 to the evaporator 7 and on the other hand through the suction tube 9 reversely to the evaporator 7. Since this high pressure and high temperature super-heated refrigerant gas is a large heat load on the evaporator 7, such out-flow of the refrigerant gas after the rotary compressor 1 stops is not desirable. Such out-flow of the refrigerant gas from the rotary compressor 1 to the outside of its housing is inevitable since the conventional rotary compressor 1 uses mechanical seals, which theoretically cannot seal the refrigerant gas completely. Thus the conventional refrigerating apparatus using a rotary compressor 1 has the shortcoming of the refrigerant gas's flowing out towards the evaporator to impose a large heat load thereto. Accordingly, even by using a rotary compressor, which has about 20% higher efficiency than a conventional reciprocal compressor, the actual electric freezer refrigerator or electric refrigerator defined in the Japanese industrial standard (JIS) C9607, which corresponds to the standard of association of home appliance manufacturers (AHAM)HRF-1, has only about 5% a power saving. In order to improve power saving, it is necessary to stop undesirable flowing of the large amount of high temperature super-heated gas from the outlet port and inlet port of the compressor 1 stops. For such purpose, the conventional improvement has been made, as shown in FIG. 2, to provide a check valve CV in the suction line 9 which is the path from the evaporator 7 to the inlet port of the rotary compressor housing 2. However, even in such improved apparatus of FIG. 2, since the path between the output port of the rotary compressor housing and the evaporator 7 has no particular means to stop undesirable flowing of the high temperature super heated refrigerant gas, power saving of only about 5% is achieved, thus achieving only about 10% overall power saving over that of the older prior art of FIG. 1.
Still another conventional improvement has been made as shown in FIG. 3, by providing an electromagnetic valve MV in the refrigerant path between the condensor 4 and the capillary tube 6, but such electromagnetic valve is expensive, makes a big noise in operation and further requires a control circuit therefore and power for its operation.